@Mohammad
My question specially to you only, I’ve been using Discourse open source application for my company and I must say it has some nice rich features that no other forums have till now. One thing I’ve noticed in my Google Analytics that it has very low bounce rate, may I know the reason why such low bounce rate showing in GA?

A Low bounce rate means that users are finding your Discourse site useful and they are spending a lot of time in it exploring the great content in it!

So it is a good news that you have such a low bounce rate which is recommended for sites to rank higher on SERPs. We have a bounce rate of 35% for this forum because users are spending a lot of time here and thus giving us more pageviews.

Bounce rate of a website = Total number of bounces across all the pages on the website / total number of entrances across all the pages on the website

A high bounce rate is what you must not have. A high BR means that users are finding your site less useful and therefore closing it after a single visit.

Do share your URL because I have never heard of a bounce rate less than 20%

Your company site must be exclusive or something might have been reported wrong at Analytics. Analytics and other Google tools like webmasters often have algorithm maintenance problems so this could have been one reason why BR is shown so less.